/*
 *  Copyright 2001-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package com.querydsl.core.util;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;

/**
 * An implementation of Map for JavaBeans which uses introspection to
 * get and put properties in the bean.
 * <p>
 * If an exception occurs during attempts to get or set a property then the
 * property is considered non existent in the Map
 * <p>
 *
 * @author James Strachan
 * @author Matt Hall, John Watkinson, Stephen Colebourne
 * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:19 $
 * @since Commons Collections 1.0
 */
@SuppressWarnings("rawtypes")
public class BeanMap extends AbstractMap<String, Object> implements Cloneable {

    private transient Object bean;

    private transient Map<String, Method> readMethods = new HashMap<String, Method>();
    private transient Map<String, Method> writeMethods = new HashMap<String, Method>();
    private transient Map<String, Class<?>> types = new HashMap<String, Class<?>>();

    /**
     * An empty array.  Used to invoke accessors via reflection.
     */
    private static final Object[] NULL_ARGUMENTS = {};

    /**
     * Maps primitive Class types to transformers.  The transformer
     * transform strings into the appropriate primitive wrapper.
     */
    private static final Map<Class<?>, Function<?,?>> defaultFunctions = new HashMap<Class<?>, Function<?,?>>();

    static {
        defaultFunctions.put(Boolean.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Boolean.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Character.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return input.toString().charAt(0);
            }
        });
        defaultFunctions.put(Byte.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Byte.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Short.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Short.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Integer.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Integer.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Long.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Long.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Float.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Float.valueOf(input.toString());
            }
        });
        defaultFunctions.put(Double.TYPE, new Function() {
            @Override
            public Object apply(Object input) {
                return Double.valueOf(input.toString());
            }
        });
    }


    // Constructors
    //-------------------------------------------------------------------------

    /**
     * Constructs a new empty {@code BeanMap}.
     */
    public BeanMap() {
    }

    /**
     * Constructs a new {@code BeanMap} that operates on the
     * specified bean.  If the given bean is {@code null}, then
     * this map will be empty.
     *
     * @param bean the bean for this map to operate on
     */
    public BeanMap(Object bean) {
        this.bean = bean;
        initialise();
    }

    // Map interface
    //-------------------------------------------------------------------------

    @Override
    public String toString() {
        return "BeanMap<" + bean + ">";
    }

    /**
     * Clone this bean map using the following process:
     * <p>
     * <ul>
     * <li>If there is no underlying bean, return a cloned BeanMap without a
     * bean.
     * <p>
     * <li>Since there is an underlying bean, try to instantiate a new bean of
     * the same type using Class.newInstance().
     * <p>
     * <li>If the instantiation fails, throw a CloneNotSupportedException
     * <p>
     * <li>Clone the bean map and set the newly instantiated bean as the
     * underlying bean for the bean map.
     * <p>
     * <li>Copy each property that is both readable and writable from the
     * existing object to a cloned bean map.
     * <p>
     * <li>If anything fails along the way, throw a
     * CloneNotSupportedException.
     * <p>
     * </ul>
     */
    @Override
    public Object clone() throws CloneNotSupportedException {
        BeanMap newMap = (BeanMap) super.clone();

        if (bean == null) {
            // no bean, just an empty bean map at the moment.  return a newly
            // cloned and empty bean map.
            return newMap;
        }

        Object newBean = null;
        Class<?> beanClass = null;
        try {
            beanClass = bean.getClass();
            newBean = beanClass.newInstance();
        } catch (Exception e) {
            // unable to instantiate
            throw new CloneNotSupportedException("Unable to instantiate the underlying bean \"" + beanClass.getName() + "\": " + e);
        }

        try {
            newMap.setBean(newBean);
        } catch (Exception exception) {
            throw new CloneNotSupportedException("Unable to set bean in the cloned bean map: " + exception);
        }

        try {
            // copy only properties that are readable and writable.  If its
            // not readable, we can't get the value from the old map.  If
            // its not writable, we can't write a value into the new map.
            for (String key : readMethods.keySet()) {
                if (getWriteMethod(key) != null) {
                    newMap.put(key, get(key));
                }
            }
        } catch (Exception exception) {
            throw new CloneNotSupportedException("Unable to copy bean values to cloned bean map: " + exception);
        }

        return newMap;
    }

    /**
     * Puts all of the writable properties from the given BeanMap into this
     * BeanMap. Read-only and Write-only properties will be ignored.
     *
     * @param map the BeanMap whose properties to put
     */
    public void putAllWriteable(BeanMap map) {
        for (String key : map.readMethods.keySet()) {
            if (getWriteMethod(key) != null) {
                this.put(key, map.get(key));
            }
        }
    }


    /**
     * This method reinitializes the bean map to have default values for the
     * bean's properties.  This is accomplished by constructing a new instance
     * of the bean which the map uses as its underlying data source.  This
     * behavior for {@code Map#clear()} differs from the Map contract in that
     * the mappings are not actually removed from the map (the mappings for a
     * BeanMap are fixed).
     */
    @Override
    public void clear() {
        if (bean == null) {
            return;
        }
        Class<?> beanClass = null;
        try {
            beanClass = bean.getClass();
            bean = beanClass.newInstance();
        } catch (Exception e) {
            throw new UnsupportedOperationException("Could not create new instance of class: " + beanClass);
        }
    }

    /**
     * Returns true if the bean defines a property with the given name.
     * <p>
     * The given name must be a {@code String}; if not, this method
     * returns false. This method will also return false if the bean
     * does not define a property with that name.
     * <p>
     * Write-only properties will not be matched as the test operates against
     * property read methods.
     *
     * @param name the name of the property to check
     * @return false if the given name is null or is not a {@code String};
     *         false if the bean does not define a property with that name; or
     *         true if the bean does define a property with that name
     */
    public boolean containsKey(String name) {
        Method method = getReadMethod(name);
        return method != null;
    }

    /**
     * Returns the value of the bean's property with the given name.
     * <p>
     * The given name must be a {@code String} and must not be
     * null; otherwise, this method returns {@code null}.
     * If the bean defines a property with the given name, the value of
     * that property is returned. Otherwise, {@code null} is
     * returned.
     * <p>
     * Write-only properties will not be matched as the test operates against
     * property read methods.
     *
     * @param name the name of the property whose value to return
     * @return the value of the property with that name
     */
    public Object get(String name) {
        if (bean != null) {
            Method method = getReadMethod(name);
            if (method != null) {
                try {
                    return method.invoke(bean, NULL_ARGUMENTS);
                } catch (IllegalAccessException | NullPointerException | InvocationTargetException | IllegalArgumentException e) {
                }
            }
        }
        return null;
    }

    /**
     * Sets the bean property with the given name to the given value.
     *
     * @param name  the name of the property to set
     * @param value the value to set that property to
     * @return the previous value of that property
     */
    @Override
    public Object put(String name, Object value) {
        if (bean != null) {
            Object oldValue = get(name);
            Method method = getWriteMethod(name);
            if (method == null) {
                throw new IllegalArgumentException("The bean of type: " + bean.getClass().getName() + " has no property called: " + name);
            }
            try {
                Object[] arguments = createWriteMethodArguments(method, value);
                method.invoke(bean, arguments);

                Object newValue = get(name);
                firePropertyChange(name, oldValue, newValue);
            } catch (InvocationTargetException | IllegalAccessException e) {
                throw new IllegalArgumentException(e.getMessage());
            }
            return oldValue;
        }
        return null;
    }

    /**
     * Returns the number of properties defined by the bean.
     *
     * @return the number of properties defined by the bean
     */
    @Override
    public int size() {
        return readMethods.size();
    }


    /**
     * Get the keys for this BeanMap.
     * <p>
     * Write-only properties are <b>not</b> included in the returned set of
     * property names, although it is possible to set their value and to get
     * their type.
     *
     * @return BeanMap keys.  The Set returned by this method is not
     *         modifiable.
     */
    @Override
    public Set<String> keySet() {
        return readMethods.keySet();
    }

    /**
     * Gets a Set of MapEntry objects that are the mappings for this BeanMap.
     * <p>
     * Each MapEntry can be set but not removed.
     *
     * @return the unmodifiable set of mappings
     */
    @Override
    public Set<Entry<String, Object>> entrySet() {
        return new AbstractSet<Entry<String, Object>>() {
            @Override
            public Iterator<Entry<String, Object>> iterator() {
                return entryIterator();
            }

            @Override
            public int size() {
                return BeanMap.this.readMethods.size();
            }
        };
    }

    /**
     * Returns the values for the BeanMap.
     *
     * @return values for the BeanMap.  The returned collection is not
     *         modifiable.
     */
    @Override
    public Collection<Object> values() {
        List<Object> answer = new ArrayList<Object>(readMethods.size());
        for (Iterator<Object> iter = valueIterator(); iter.hasNext();) {
            answer.add(iter.next());
        }
        return answer;
    }


    // Helper methods
    //-------------------------------------------------------------------------

    /**
     * Returns the type of the property with the given name.
     *
     * @param name the name of the property
     * @return the type of the property, or {@code null} if no such
     *         property exists
     */
    public Class<?> getType(String name) {
        return types.get(name);
    }

    /**
     * Convenience method for getting an iterator over the keys.
     * <p>
     * Write-only properties will not be returned in the iterator.
     *
     * @return an iterator over the keys
     */
    public Iterator<String> keyIterator() {
        return readMethods.keySet().iterator();
    }

    /**
     * Convenience method for getting an iterator over the values.
     *
     * @return an iterator over the values
     */
    public Iterator<Object> valueIterator() {
        final Iterator<String> iter = keyIterator();
        return new Iterator<Object>() {
            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public Object next() {
                Object key = iter.next();
                return get(key);
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException("remove() not supported for BeanMap");
            }
        };
    }

    /**
     * Convenience method for getting an iterator over the entries.
     *
     * @return an iterator over the entries
     */
    public Iterator<Entry<String, Object>> entryIterator() {
        final Iterator<String> iter = keyIterator();
        return new Iterator<Entry<String, Object>>() {
            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public Entry<String, Object> next() {
                String key = iter.next();
                Object value = get(key);
                return new MyMapEntry(BeanMap.this, key, value);
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException("remove() not supported for BeanMap");
            }
        };
    }


    // Properties
    //-------------------------------------------------------------------------

    /**
     * Returns the bean currently being operated on.  The return value may
     * be null if this map is empty.
     *
     * @return the bean being operated on by this map
     */
    public Object getBean() {
        return bean;
    }

    /**
     * Sets the bean to be operated on by this map.  The given value may
     * be null, in which case this map will be empty.
     *
     * @param newBean the new bean to operate on
     */
    public void setBean(Object newBean) {
        bean = newBean;
        reinitialise();
    }

    /**
     * Returns the accessor for the property with the given name.
     *
     * @param name the name of the property
     * @return the accessor method for the property, or null
     */
    public Method getReadMethod(String name) {
        return readMethods.get(name);
    }

    /**
     * Returns the mutator for the property with the given name.
     *
     * @param name the name of the property
     * @return the mutator method for the property, or null
     */
    public Method getWriteMethod(String name) {
        return writeMethods.get(name);
    }


    // Implementation methods
    //-------------------------------------------------------------------------

    /**
     * Reinitializes this bean.  Called during {@link #setBean(Object)}.
     * Does introspection to find properties.
     */
    protected void reinitialise() {
        readMethods.clear();
        writeMethods.clear();
        types.clear();
        initialise();
    }

    private void initialise() {
        if (getBean() == null) {
            return;
        }

        Class<?> beanClass = getBean().getClass();
        try {
            //BeanInfo beanInfo = Introspector.getBeanInfo( bean, null );
            BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            if (propertyDescriptors != null) {
                for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
                    if (propertyDescriptor != null) {
                        String name = propertyDescriptor.getName();
                        Method readMethod = propertyDescriptor.getReadMethod();
                        Method writeMethod = propertyDescriptor.getWriteMethod();
                        Class<?> aType = propertyDescriptor.getPropertyType();

                        if (readMethod != null) {
                            readMethods.put(name, readMethod);
                        }
                        if (writeMethods != null) {
                            writeMethods.put(name, writeMethod);
                        }
                        types.put(name, aType);
                    }
                }
            }
        } catch (IntrospectionException e) {

        }
    }

    /**
     * Called during a successful {@link #put(Object,Object)} operation.
     * Default implementation does nothing.  Override to be notified of
     * property changes in the bean caused by this map.
     *
     * @param key      the name of the property that changed
     * @param oldValue the old value for that property
     * @param newValue the new value for that property
     */
    protected void firePropertyChange(String key, Object oldValue, Object newValue) {
    }

    // Implementation classes
    //-------------------------------------------------------------------------

    /**
     * Map entry used by {@link BeanMap}.
     */
    protected static class MyMapEntry implements Map.Entry<String, Object> {
        private final BeanMap owner;

        private String key;

        private Object value;

        /**
         * Constructs a new <code>MyMapEntry</code>.
         *
         * @param owner the BeanMap this entry belongs to
         * @param key   the key for this entry
         * @param value the value for this entry
         */
        protected MyMapEntry(BeanMap owner, String key, Object value) {
            this.key = key;
            this.value = value;
            this.owner = owner;
        }

        /**
         * Sets the value.
         *
         * @param value the new value for the entry
         * @return the old value for the entry
         */
        @Override
        public Object setValue(Object value) {
            String key = getKey();
            Object oldValue = owner.get(key);

            owner.put(key, value);
            Object newValue = owner.get(key);
            this.value = newValue;
            return oldValue;
        }

        @Override
        public String getKey() {
            return key;
        }

        @Override
        public Object getValue() {
            return value;
        }
    }

    /**
     * Creates an array of parameters to pass to the given mutator method.
     * If the given object is not the right type to pass to the method
     * directly, it will be converted using {@link #convertType(Class,Object)}.
     *
     * @param method the mutator method
     * @param value  the value to pass to the mutator method
     * @return an array containing one object that is either the given value
     *         or a transformed value
     * @throws IllegalAccessException   if {@link #convertType(Class,Object)}
     *                                  raises it
     * @throws IllegalArgumentException if any other exception is raised
     *                                  by {@link #convertType(Class,Object)}
     */
    protected Object[] createWriteMethodArguments(Method method, Object value) throws IllegalAccessException {
        try {
            if (value != null) {
                Class<?>[] types = method.getParameterTypes();
                if (types != null && types.length > 0) {
                    Class<?> paramType = types[0];
                    if (paramType.isPrimitive()) {
                        paramType = PrimitiveUtils.wrap(paramType);
                    }
                    if (!paramType.isAssignableFrom(value.getClass())) {
                        value = convertType(paramType, value);
                    }
                }
            }
            return new Object[]{value};
        } catch (InvocationTargetException | InstantiationException e) {
            throw new IllegalArgumentException(e.getMessage());
        }
    }

    /**
     * Converts the given value to the given type.  First, reflection is
     * is used to find a public constructor declared by the given class
     * that takes one argument, which must be the precise type of the
     * given value.  If such a constructor is found, a new object is
     * created by passing the given value to that constructor, and the
     * newly constructed object is returned.<P>
     * <p>
     * If no such constructor exists, and the given type is a primitive
     * type, then the given value is converted to a string using its
     * {@link Object#toString() toString()} method, and that string is
     * parsed into the correct primitive type using, for instance,
     * {@link Integer#valueOf(String)} to convert the string into an
     * {@code int}.<P>
     * <p>
     * If no special constructor exists and the given type is not a
     * primitive type, this method returns the original value.
     *
     * @param newType the type to convert the value to
     * @param value   the value to convert
     * @return the converted value
     * @throws NumberFormatException     if newType is a primitive type, and
     *                                   the string representation of the given value cannot be converted
     *                                   to that type
     * @throws InstantiationException    if the constructor found with
     *                                   reflection raises it
     * @throws InvocationTargetException if the constructor found with
     *                                   reflection raises it
     * @throws IllegalAccessException    never
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    protected Object convertType(Class<?> newType, Object value) throws InstantiationException, IllegalAccessException, InvocationTargetException {
        // try call constructor
        Class<?>[] types = {value.getClass()};
        try {
            Constructor<?> constructor = newType.getConstructor(types);
            Object[] arguments = {value};
            return constructor.newInstance(arguments);
        } catch (NoSuchMethodException e) {
            // try using the transformers
            Function function = getTypeFunction(newType);
            if (function != null) {
                return function.apply(value);
            }
            return value;
        }
    }

    /**
     * Returns a transformer for the given primitive type.
     *
     * @param aType the primitive type whose transformer to return
     * @return a transformer that will convert strings into that type,
     *         or null if the given type is not a primitive type
     */
    protected Function<?,?> getTypeFunction(Class<?> aType) {
        return defaultFunctions.get(aType);
    }

}
